1. Field of the Invention
This invention relates to methods and apparatus for the production of novel and improved carpet yarns, and more particularly, to the production of heavy denier continuous filament yarns for cut-pile carpets, although the processes herein described may also have application to the production of yarns for other purposes, such as spun yarns for handknitting.
2. Prior Art
The process described herein has been found to have especially significant application in the field of yarns which are produced from synthetic filament yarns which have been "pre-bulked" by the producer thereof in connection with the yarn spinning and manufacturing processes. Such yarns, produced and sold, for example, by the E. I. DuPont de Nemours Company, are known in the trade as "BCF" yarns, meaning "bulked continuous filament" yarns. These are yarns which have been endowed with certain properties by the yarn producers in the manufacturing processes, by heretofore unspecified means, which result in such filament yarns possessing certain latent tendencies to subsequently crimp or deform under the application of certain conditions of heat and moisture.
It has been found, however, that BCF yarns should not be initially subjected to temperature conditions that are overly severe, so that these yarns, which also have thermoplastic properties, do not become "set" prior to or concurrently with the onset of the manifestation or development of the theretofore latent properties in the yarn. Moreover, it is known that the application of linear tensions, such as are common in the continuous processing of yarns, during the period of the supposed development of manifest crimp will significantly retard or even suppress entirely the development of the full crimp properties possessed by the BCF yarns.
It has also been found that the crimp characteristics of BCF yarns, once developed and made manifest, are extremely fragile and can still be distorted, damaged, or even destroyed altogether by the subsequent handling processes which are commonly employed in the textile trade. For purposes of an illustrative example, a synthetic or thermoplastic yarn which is texturized in the currently widely employed false-twist process is continuously subjected to linear tensions on the order of at least 0.06 grams/denier, and the yarn, after receiving its manifest crimp by removal of twist, is usually subjected to tensions of about 0.4 grams/denier or higher without, however, materially adversely affecting the final texture or crimp in the finished yarn. Such tensions, applied to BCF yarns, upon the manifestation of their crimp characteristics, simply straighten and permanently remove the crimped deformations, thereby rendering the yarn substantially untexturized, and in any event, entirely unsuitable for the desired end uses.
Heretofore, all of the known processes for producing commercially suitable yarns for BCF yarns have been limited by the factors mentioned above, to the step-by-step formation, handling and multiple treatment of discrete hanks or skeins of the yarn. These known processes, and the resulting yarn products, are subject to a plurality of inherent defects, deficiencies and inefficiencies. Among these are the following: (a) loss of significant latent crimp properties, which are never developed and made manifest in the yarn; (b) removal and eventual loss of manifested crimp by the required subsequent handling processes; (c) nonuniform development of manifest crimp; (d) non-uniformity of dye-uptake, resulting in "streakiness" in the finished product; and (e) excessive costs due to the number of handling operations and treatments that must be applied to obtain yarns of minimum suitability for the desired end use.
Accordingly, it is an object of the present invention to provide a method for processing BCF yarns so as to initially develop and render manifest, and to a significantly greater extent than previously possible, substantially all of the latent properties induced therein by the yarn producer; for further processing the yarns, without substantially degrading or damaging the latent properties which have been rendered manifest; and for permanently fixing or setting the thus manifest properties so as to produce yarns useful for carpets and the like which retain their full, uniform, bulk and crimp throughout subsequent finishing and manufacturing operations and display significantly improved and durable bulk and "cover" while in service.
It is a further object of the invention to provide a method for bulking and setting BCF yarns in a continuous process which substantially reduces the number of lengthy and expensive operations required by previously-known processes.
It is a further object to provide carpet yarns for cut-pile carpets and the like which display substantially increased bulk and cover, as compared with like yarns of the same weight which are produced by prior art methods.
It is a further object of the present invention to provide carpet yarns for cut-pile carpets and the like which display unique aesthetic qualities and improved covering properties, as compared to like yarns produced by previously-known methods, by reason of an irregular linear formation permanently set in the yarns.
It is a still further object to provide means and apparatus for efficiently and economically carrying out the methods herein disclosed, and achieving these and other objects of the present invention.